Improper Repair Of Floor Joists

Generally there should never be any cuts or penetrations in the middle third of any joist or anywhere along the bottom of the joist.

Improper repair of floor joists.

A common but improper repair by other contractors is to install more full length joists. Jacking them up too fast may cause cracks in the walls and floors overhead. Total costs will depend on the extent of the damage and the ease of access to the joists through a basement or crawlspace but in general sistering averages 100 300 or more per joist and could run 1 000 3 000 or more to repair a tilted wavy or bouncy floor under an average room. Make sure not to install joists so they run parallel to and directly under walls where you intend to install ductwork.

Improper notching can weaken a floor joist. Set a hydraulic jack and post under the beam and jack up the joists about 1 8 in. Take some extra time and jack the damaged area up so that the new lumber doesn t need to be notched. The notch was made where the floor joist recessed into a wood beam supported by chimney corbeling.

Tack a beam under the sagging joists. A day until they re level. This will not work as the joist was not designed for this load originally. Improper holes and notches from alterations and running service lines are a major source of weakened joists.

Notches at the end of a joist should not exceed 1 4 of the joist depth. In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place. Corbeling is an old school overlapping arrangement of bricks with each course extending farther out from the vertical of the wall than the course below. Use common sense when deciding how many fasteners to use.

Floor is sinking between the floor joists. Splicing with plywood can have some advantages over splicing with a solid joist in many situations. Nailing two 2x4s together will work to span about three joists unless the sag is under a weight bearing wall. Position bathroom vent fans so the ducts can run parallel to the joists right up to where they exit the house.

Pictured is joist repair method for end rotted joist using plywood and some suggestions for best practice. Finally if all else fails drop your pipes and ducts down below the joists and box them in with wood framed soffits.